my house was built in 1900. i dont know when the basement was added, maybe in the '50's, unsure. anyway, where i have joists above the basement window, they sag. there is absolutely NO support. in the research i have done, i have noticed that most homes have a sill plate...my house does not. it seems as though they just built the foundation walls and set the house on them and hoped for the best. i try to look at other homes that appear to be the same age as mine, but you cant really tell anything unless you can get right up to it and look at it. i have asked some people, they have said to get a piece of angle iron to place between the sill (which i dont have) and the bricks. when i look at brick buildings i see the iron on top of the windows. i want to fix it myself, but i need help. i have some ideas, im just wondering if anyone has encountered the same problem as me and if they have any pointers. please take a look at the photos. im trying to show the amount of sag with my finger. thanks

Welcome J. A. Neil:
You need a 4 X 6 and 2 basement jacks. Put the 4 X 6 across the floor joists with a basement jack at each side of the window, about a foot from the end of the joists. Raise the joists 3/8" off the wall and insert the angle iron upside down, making sure it has at least 8" of bearing on the wall on each side of the window.
Now go upstairs and see if there is too much of a hump in the floor where there used to be a sag. If there is too much of a hump; remove the angle iron and cut the 3/8" off the bottom of the joists ( a recriprocating saw works well in this case). Then replace the angle iron and let the jacks down.
Thanks for the pictures, they make it soooo much easier to answer the question. Maybe you can get a couple of after pictures too.
Happy New Year!
Glenn